【作者】 严柯科；

【导师】 何晓聪；

【作者基本信息】 昆明理工大学 ， 机械制造及其自动化， 2011， 硕士

【摘要】 自冲铆接是一种很有潜力的连接工艺,尤其对于轻型材料(轻合金、复合材料等)的连接。自冲铆接采用冲头将一个半空心的铆钉压入板材,铆钉管腿端部在嵌入板材的过程中喇叭状张开变形,在两层板或多层板中形成机械内锁,从而将上板和下板牢固地连接在一起。尽管自冲铆技术是一种新型的薄板连接技术,但它的机械性能比传统的点焊好。自冲铆技术被誉为下一代连接技术,是汽车轻量化过程中的一项关键技术,已在汽车行业得到广泛的应用。本论文利用数值模拟方法及实验方法研究了自冲铆接成型过程。用有限元软件LS-DYNA基于Cowper-Symonds材料模型建立了2D模型,用Lagrange方法及r-自适应网格划分技术模拟了整个铆接成型过程。结合铆接实体实验的载荷-位移曲线及接头剖面图验证了数值模拟的合理性。分析了凹模凸台尺寸、铆钉尺寸、动静摩擦系数、塑性应变比等参数对成型的影响,从而可以更好的对铆接过程的参数进行优化设计。利用有限元软件ANSYS对自冲铆接头进行静力学分析、动力学分析及疲劳分析。通过静力学分析得出最大应力主要分布在上下两板相互接触靠近铆钉孔的位置及上板与铆钉头部相接触的位置。对模态振型的研究提取了前25阶振型,分析得到横向振动的偶数振型关于两板搭接位置对称,搭接位置处在振型的峰值处。说明两板搭接位置对白冲铆接的机械性能有较大的影响,是疲劳分析的关键位置。对自冲铆接试件进行了拉伸剪切实验。通过对4组数据的研究对比发现,2系列铝合金自冲铆接-粘接试件的静态拉伸强度大于2系列铝合金自冲铆接试件。2系列铝合金自冲铆接试件的静态拉伸强度大于2系列铝合金压印连接试件。5系列铝合金自冲铆接试件的静态拉伸强度超过了5000N。为下阶段自冲铆接头的疲劳分析提供了应力信息。利用ANYSY/FE-SAFE有限元软件对5052铝合金自冲铆接头进行了疲劳分析。研究显示：疲劳破坏常常在上下两板相互接触靠近铆钉孔的位置,以及上板与铆钉头部接触并靠近铆钉孔的位置。通过ANSYS/LS-DYNA软件模拟了铆接接头裂纹扩展的整个过程。本文主要目的是实现自冲铆接头动力学数值模拟及疲劳分析,为更深一步的研究提供基础。更多还原

【Abstract】 The self-piercing riveting(SPR) is a potential connection technology, especially for the connection of the light material(light alloy, composite material etc). SPR uses a punch forcing a semi-tubular rivet into the sheets, the rivet shank expansion and deformation like trumpet in the embedded process, forming a interlock between the two sheets or multilayer sheets, thus the upper sheet and the lower sheet connected together firmly. Though SPR is a new-type connection technique for sheets, the mechanical properties of it is better than the traditional spot welding. It known as the next generation connection technique is a key technology in the lightweight procedure of automobile, applied comprehensive in the auto industry.The molding process of the SPR used numerical method and experimental were approached in this paper. FEM software LS-DYNA based on Cowper-Symonds material model was used to built 2D model, and Lagrange method and r-self-adaptive mesh technique were used to simulate the whole shaping process of the riveting. The load displacement diagram of riveting experiment and the section of joint validated the rationality of the numerical simulation.This paper analyzed the influence of the parameter on shaping including the concave die and the convex platform, the dimension of the rivet, the static and dynamic friction coefficient, plastic strain ratio and so on, consequently making optimum design for the parameter of the riveting process better.The ANSYS software was used to investigate the mechanical property including statics analysis, dynamics analysis and fatigue analysis. Statics analysis obtained the maximum stress mainly distributed in the location where the two sheets contacted and closed to rivet hole, the upper sheet and the rivet head contacted and closed to rivet hole. From the modal analysis which extracted the first twenty-five mode shape, the odd shapes of the transverse vibration shown symmetry between the lap position for the two sheets, and the lap position located at the peak of shapes. It was explained that the lap position influenced the dynamic property of single lap-jointed SPR greatly, was the key location for fatigue analysis.The tensile shear experiments on specimens were made. Compared with 4 group data, the static tensile strength of the 2 series aluminum alloy SPR-adhesive bonded pieces were bigger than the 2 series aluminum alloy SPR pieces. The static tensile strength of the 2 series aluminum alloy SPR pieces were bigger than the 2 series aluminum alloy clinched pieces. The static tensile strength of the 5 series aluminum alloy SPR pieces exceeded 5000N. It provided enough preparatory work for the fatigue analysis of the joints in the future research.ANYSY/FE-SAFE was used to made fatigue analysis for SPR joints. From the fatigue performance analysis of the 5052 aluminum alloy single lap-jointed SPR found that fatigue damage existed in the location where the two sheet contacted and closed to rivet hole, the upper sheet and the rivet head contacted and closed to rivet hole. The FEM software ANSYS/LS-DYNA was used to simulate the whole crack propagation process of the riveting joint.The purpose of this paper was to realize the dynamics numerical simulation and fatigue analysis of the SPR joints, providing foundation for further research.更多还原